1. Field of the Invention
This invention relates to a semiconductor laser, and more particularly to a semiconductor laser with rib waveguide structure.
2. Description of the Related Art
Recently, a semiconductor laser has been widely used and a semiconductor laser with rib waveguide structure has been used in various application fields. The construction of the semiconductor laser with rib waveguide structure is disclosed in, for example, ELECTRONICS LETTERS Aug. 27th, 1987 Vol. 23 No. 18 P.938 and 939 "HIGH-POWER OPERATION OF A TRANSVERSE-MODE STABILIZED AlGaInP VISIBLE LIGHT (.lambda..sub.L =683 nm) SEMICONDUCTOR LASER".
However, in the semiconductor laser shown in FIG. 1 of the above document, a heterojunction is formed between a p - (Al.sub.0.6 Ga.sub.0.4).sub.0.5 In .sub.0.5 P layer and a p-GaAs layer, that is, between an upper cladding layer and the bottom portion of an ohmic layer. Since a large voltage drop occurs across the heterojunction portion, the power consumption may become large and the heterojunction portion tends to generate heat, degrading the temperature characteristic of the semiconductor laser.